JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<head>
    <script type="text/javascript" src="http://lib.ivank.net/ivank.js"></script>
    <script type="text/javascript">
        var stage, s, dragged;
        var c1, c2, c3, c4;     // anchors for Cubic BĂ©zier
        
        function Start()
        {
            stage = new Stage("c");
            s = new Sprite();
            stage.addChild(s);
            
            c1 = new Dot("A");  c2 = new Dot("B");  c3 = new Dot("C");  c4 = new Dot("D");
            var ds = [c1, c2, c3, c4];
            for(var i=0; i<ds.length; i++)
            {
                ds[i].x = 50+i*120;  ds[i].y = 200-100*Math.sin(i*1.2);
                ds[i].addEventListener(MouseEvent.MOUSE_DOWN, onMD);
                s.addChild(ds[i]);
            }
            stage.addEventListener(MouseEvent.MOUSE_MOVE, onMM);
            stage.addEventListener(MouseEvent.MOUSE_UP, onMU);
            redraw();
        }
        
        function onMD(e){dragged = e.target;}
        function onMU(e){dragged = null;    }
        function onMM(e)
        {
            if(dragged == null) return;
            dragged.x = stage.mouseX;  dragged.y = stage.mouseY;
            redraw();
        }
        
        function redraw()
        {
            with(s.graphics)
            {
                clear();
        
                var r = getCurveBounds(c1.x, c1.y, c2.x, c2.y, c3.x, c3.y, c4.x, c4.y);
                beginFill(0x00ff00, 0.2);
                drawRect(r.x, r.y, r.width, r.height);   
                endFill();
        
                lineStyle(2, 0x999999);    //  two "skeletons"
                moveTo(c1.x, c1.y);
                lineTo(c2.x, c2.y);  lineTo(c3.x, c3.y);  lineTo(c4.x, c4.y);
                
                lineStyle(7, 0x00aaff);
                moveTo(c1.x, c1.y);
                cubicCurveTo(c2.x, c2.y, c3.x, c3.y, c4.x, c4.y);
            }
        }
        
        function Dot(name)
        {
            Sprite.call(this);  // inherits from Sprite
   ...